Human body blood cells

Blood cells. Blood and the linings of blood vessels may be regarded as a fifth tissue type.135/135a The human body contains 5 x 109 erythrocytes or red blood cells per ml, a total of 2.5 x 1013 cells in the five liters of blood present in the body. Erythrocytes are rapidly synthesized in the bone marrow. The nucleus is destroyed, leaving a cell almost completely filled with hemoglobin. With an average lifetime of 125 days, human red blood cells are destroyed by leukocytes in the spleen and liver. 

What is the likelihood that other elements will be found essential Consider a human red blood cell, an object of volume 80 pm3 and containing about 3 x 108 protein molecules (mostly hemoglobin). About 7 x 105 atoms of the "trace metal" copper and 105 atoms of the nutritionally essential tin are present in a single red cell. Also present are 2 x 104 atoms of silver, a toxic metal. Its concentration, over 10 7 M, is sufficient that it could have an essential catalytic function. However, we know of none and it may simply have gotten into our bodies from handling money, jewelry, and other... 

Making different kinds of cells—muscle, skin, bone, neuron, blood cells—is not enough to produce the human body. The cells must be properly arranged and organized into tis-... 

Human red blood cells have a diameter of approximately 6 to 8 pm. The human body, however, contains capillaries approximately 3 pm in diameter. To pass through these vessels the blood cells have to deform correspondingly. Healthy cells will do this readily but malignant cells will not. By filtering blood through a 3 pm capillary pore membrane certain blood deficiencies can be monitored.16... 

In the human body, many cells cycle frequently, e.g., hair follicles, skin cells, and cells of the duodenal crypts. Other cells, such as the precursors of red blood cells, divide a number of times, then lose their nuclei and leave the cell cycle to form mature red blood cells. These cells transport oxygen and carbon dioxide between the lungs and other tissues for about 120 days, then die. Other cells are normally quiescent (in Gq). However, they can be stimulated to divide. In many instances, the stimuli are growth factors or hormones (e.g., mammary aveolar cells and uterine cells). In the case of liver cells, the stimulus is produced by death of some of the cells. 

Human blood is a very complex fluid which contains about 0.04% P and has a pH of about 7.4. It acts as a transport medium for oxygen and carbon dioxide, food, waste products, enzymes hormones etc. An average 70 kg man contains 5.2 L which constitutes 6-8% of the total body weight. This can be separated into blood cells (red + white + platelets) and plasma, by centrifuging (Figure 11.4). The average lifetime of a human red blood cell is -120 days (Table 11.6). 

Phosphorus. Eighty-five percent of the phosphoms, the second most abundant element in the human body, is located in bones and teeth (24,35). Whereas there is constant exchange of calcium and phosphoms between bones and blood, there is very Httle turnover in teeth (25). The Ca P ratio in bones is constant at about 2 1. Every tissue and cell contains phosphoms, generally as a salt or ester of mono-, di-, or tribasic phosphoric acid, as phosphoHpids, or as phosphorylated sugars (24). Phosphoms is involved in a large number and wide variety of metaboHc functions. Examples are carbohydrate metaboHsm (36,37), adenosine triphosphate (ATP) from fatty acid metaboHsm (38), and oxidative phosphorylation (36,39). Common food sources rich in phosphoms are Hsted in Table 5 (see also Phosphorus compounds). 

Zinc. The 2—3 g of zinc in the human body are widely distributed in every tissue and tissue duid (90—92). About 90 wt % is in muscle and bone unusually high concentrations are in the choroid of the eye and in the prostate gland (93). Almost all of the zinc in the blood is associated with carbonic anhydrase in the erythrocytes (94). Zinc is concentrated in nucleic acids (90), and found in the nuclear, mitochondrial, and supernatant fractions of all cells. 

In the tissues of animals, most thiamine is found as its phosphorylated esteis (4—6) and is piedominandy bound to enzymes as the pyrophosphate (5), the active coen2yme form. As expected for a factor involved in carbohydrate metaboHsm, the highest concentrations ate generally found in organs with high activity, such as the heart, kidney, Hver, and brain. In humans this typically amounts to 1—8 p.g/g of wet tissue, with lesser amounts in the skeletal muscles (35). A typical healthy human body may contain about 30 mg of thiamine in all forms, about 40—50% of this being in the muscles owing to their bulk. Almost no excess is stored. Normal human blood contains about 90 ng/mL, mostly in the ted cells and leukocytes. A value below 40 ng/mL is considered indicative of a possible deficiency. Amounts and proportions in the tissues of other animal species vary widely (31,35). 

The absorption, distribution, and accumulation of lead in the human body may be represented by a three-part model (6). The first part consists of red blood cells, which move the lead to the other two parts, soft tissue and bone. The blood cells and soft tissue, represented by the liver and kidney, constitute the mobile part of the lead body burden, which can fluctuate depending on the length of exposure to the pollutant. Lead accumulation over a long period of time occurs in the bones, which store up to 95% of the total body burden. However, the lead in soft tissue represents a potentially greater toxicological hazard and is the more important component of the lead body burden. Lead measured in the urine has been found to be a good index of the amount of mobile lead in the body. The majority of lead is eliminated from the body in the urine and feces, with smaller amounts removed by sweat, hair, and nails. 

The human body generates a steady flow of acidic by-products during its normal metabolic processes. Foremost among these is carbon dioxide, which is a major product of the reactions the body uses to produce energy (see Section 14-). An average person produces from 10 to 20 mol (440 to 880 g) of CO2 every day. Blood carries CO2 from the cells to the lungs to be exhaled. In aqueous solution, dissolved CO2 is in equilibrium with carbonic acid H2 O + CO2 H2 CO3... 

Studies have shown that in patients with chemotherapy-related anemia, therapy with erythropoietin products (epoetin-alfa and darbepoetin) can increase hemoglobin, decrease transfusion requirements, and improve quality of life.12 Epoetin is recombinant human erythropoietin, and darbepoetin is structurally similar to endogenous erythropoietin. Both bind to the same receptor to stimulate red blood cell production. Darbepoetin differs from epoetin in that it is a glycosylated form and exhibits a longer half-life in the body. The half-lives of a single subcutaneous injection of epoetin or darbepoetin in patients are roughly 27 and 43 hours, respectively. 

Immunological and Lymphoreticular Effects. Depressed white blood cell counts have been observed in humans and animals exhibiting relatively high body burdens of241 Am following accidental or... 

Symptoms of intoxication in humans caused by accidental ingestion of Kou-Wen plants have been described as follows. The effect on the digestive system starts with loss of appetite and turn of the stomach, and continues to severe abdominal pain and intestinal bleeding. The effect on the respiratory system presents as breathing difficulties which finally lead to death by respiratory failure. The effect on muscle innervation usually results in generalized muscular weakness and paralysis of the limbs. The effect on the circulatory system starts with heartbeat disorders and a drop in blood pressure, but heart failure is not a common cause of death. In addition to dilation of pupils, a drop in body temperature and proliferation of white blood cells have also been obseryed (70). 

Red blood cells owe their color to the iron complex heme, a component of hemoglobin. This provides the human body with oxygen, right up to the finest capillary. In the absence of oxygen, the blood goes dark red (venous blood). 

There are different types of cholinesterases in the human body, and they differ in their location in tissues, substrate affinity, and physiological function. The main ones are ACHE, present in nervous tissue and red blood cells (RBC-ACHE), and plasma cholinesterases (PCHE), present in glial cells, plasma, and liver. The physiological functions of RBC-ACHE and PCHE, if any, are unknown. 

The most numerous of the cellular elements in the blood are the erythrocytes (red blood cells). On average, there are 5 million red blood cells per microliter (pi) of blood, or a total of about 25 to 30 trillion red blood cells in the adult human body. The percentage of the blood made up of red blood cells is referred to as hematocrit. An average hematocrit is about 45% (42% females, 47% males). As such, the viscosity of the blood is determined primarily by these elements. 

The abundance of tin in sea water is below 3 jxg 1 1. Typical abundance of tin in the human (adult) body is 17-130 mg tin distribution is 25% in skin and lipo-tissues 3.2% in red blood cell 0.8% in blood plasma the remainder in soft tissues9. 

---